chemistry

• A decomposition reaction involves a compound breaking down into two or more simpler substances.
• A solution that has a pH greater than 7 is considered a basic (alkaline) solution.
• A solution that has a pH less than 7 is considered an acidic solution.
• The pH scale is logarithmic, with each whole number representing a tenfold change in acidity or alkalinity.
• In a gas, molecules move freely and randomly, filling their container.
• Chemical reactions involve the breaking and forming of chemical bonds.
• Decomposition reactions can be exothermic, meaning they release energy as heat.
• An example of an acidic substance is hydrochloric acid (HCl), which dissociates in water to form H+ ions.
• Strong acids completely dissociate in water, releasing all their hydrogen ions.
• Acids are proton donors, while bases are proton acceptors.
• An example of a base is sodium hydroxide (NaOH), which reacts with acids to produce salt and water.
• Weak acids only partially dissociate in water to form hydrogen ions (H+).
• Liquids have particles close together and are not easily compressed.
• Gases can be compressed to take up less space but will expand when released from the pressure.
• Solids have particles packed closely together and do not flow unless under extreme conditions.
• Protons have a positive charge (+1), while neutrons have no charge.
• Electrons have a negative charge (-1).
• common bases

  drain cleaners sodium hydroxide NaOH

  household cleaners ammonia NH3

  antacid tablets calcium carbonate CaCO3

  baking powder sodium bicarbonate NaHCO3

  washing powder sodium carbonate NaCO3
• common indicators

  thymol blue 1.2-2.8

  methyl red 4.4-6.2

  bromothymol blue 6.0-7.6

  thymol blue second transition 8.0-9.6

  phenopthalein 8.3-10.0
• natural indicator

  red cabbage

  boil cabbage and extract dye into solutions of known ph
• acid reactions

  acid +base -salt +water

  acid + carbonate- salt + water + carbon dioxide gas

  acid + metal - salt + hydrogen gas
• enthalpy of neutralisation reactions

  write the equation

  calculate the mols of water

  calculate the heat of neutralisation Q=mcat

  calculate the enthalpy of neutralisation q\mole of water
• lavoisier to humphry

  lavoiser first to define acid to contain oxygen

  davy discovers various acids do not contain oxygen but all contain hydrogen